1. Field of the Invention
The present invention relates to a pump or pumping assembly, arrangement or combination; and more particularly relates to a new technique for sealing a shaft in such a pump or pumping assembly, arrangement or combination, e.g., including a vertical double-suction pump.
2. Brief Description of Related Art
Techniques for sealing shafts are known in the art.
For example, marine shaft sealing technology is known that uses a bellows type mechanical face seal to prevent water from entering the boat hull by way of the propeller shaft. In this known propeller shaft sealing application, the seal faces seal water out of the boat and the faces are cooled by water entering from the inside diameter of the axial clearance between the faces.
In addition, existing industry pump shaft sealing technology is known that uses commercial lip seals to isolate the lubricating oil from the pumpage. However, problems with the existing industry pump shaft sealing technology include the following:
1) During operation, a commercial lip seal achieves only a temporary sealing condition because it uses a radial clearance between the stationary rubber element and the rotating shaft. The rubber elements of lip seals wear rapidly due to abrasion, which allows oil to drain out of the enclosing tube.
2) During idle conditions, a new lip seal retains lubricating oil within the enclosing tube. However, after several weeks of pump operation, the open clearance of a worn lip seal allows the oil to exit and dirty sump fluid to enter into the enclosing tube due to Archimedes' principle.
3) Lip seals rely on a continuous injection of new lubricating oil to purge and restrict dirty sump fluid from the enclosing tube. Oil continually leaks into the environment to compensate for the open radial clearance between the rubber element and the shaft.
Furthermore, shaft sealing arrangements based at least partly on using a spring arrangement are known in the art, by way of example, see U.S. Pat. No. 5,562,406. Sealing arrangements using bellows seals are also known in the art, by way of example, see U.S. Pat. No. 6,422,822.
In view of the aforementioned, there is a long felt need in the industrial pump industry for an improved design or technique that solves the problems related to sealing a shaft in an industrial pump or pumping assembly, arrangement or combination, including a vertical double-suction pump.